1. Field of the Invention
The present invention relates to improvements in or relating to yarn-gripper devices mounted on the weft-passing member in weaving looms comprising fixed weft magazines.
2. History of the Related Art
In order to obtain large-width industrial fabrics made from yarns presenting a relatively large diameter combined with a certain rigidity, weaving looms of conventional type are known to be generally employed in which the weft-passing member is constituted by a false shuttle thrown through the shed by two lateral sticks. The looms are equipped with two fixed weft magazines and the false shuttle is provided with a yarn-gripping device adapted to grip the yarn of one of the magazines at the corresponding selvedge and to release it at the opposite selvedge.
A conventional yarn-gripper device is illustrated in FIG. 1 of the accompanying drawings. The yarn-gripper device generally comprises a small frame 1 which is fixed against the lower face of the false shuttle 2 and which extends laterally on the side thereof opposite the batten of the loom. On a pivot 3 oriented parallel to the axis of the false shuttle 2, there is articulated a jaw element 4 of complex profile, adapted to define in cross-section:
a mobile jaw 4a adapted to cooperate with a fixed jaw la provided on frame 1;
a flange 4b facing away from jaw 4a and subjected to the elastic action of vertical pushers 5 which tend to apply the jaw 4a continuously against jaw la;
and a vertical actuation heel 4c housed with clearance inside a longitudinal groove 2a in the body of the false shuttle 2.
The device is opened with the aid of one or the other of two shoes 6 fixed on the sides of the loom and sectioned so as to engage in the groove 2a in the false shuttle and thus to bear against heel 4c. The whole of the jaw element 4 subsequently pivots about pivot 3 against the elastic pushers 5, which has for its effect momentarily to move jaw 4a away from jaw la and to release the weft yarn which was gripped therebetween.
It will be readily appreciated that, in order to ensure efficient gripping despite the resistance to unwinding exerted by the yarn, it is necessary to associate very powerful springs 7 with the pushers 5. Under these conditions, it is clear that the effort that each shoe 6 must exert on heel 4c is very great, which results, on the one hand, in the false shuttle being considerably slowed down in its stroke, and, on the other hand, in rapid wear of the shoes.